A torque converter which is mounted on a vehicle transmits the power of an engine to a transmission via a fluid. The torque converter is provided with a turbine blade, a stator blade, and an impeller blade. The stator blade controls the fluid so that a desirable flow of fluid flows into an inlet of the impeller blade.
As illustrated in FIG. 11A, since a torque converter of the related art has a narrow interval between stator blades 11, fluid is likely to run along a shape of the stator blade 11, and the fluid is likely to be controlled. However, as illustrated in FIG. 11B, a torque converter in recent years has had a wide interval between the stator blades 11 in order to make a manufacturing process easy. Therefore, in the vicinity of an intermediate part between one stator blade 11 and an adjacent stator blade 11, a flow of fluid which does not run along the shape of the stator blade 11 is also generated.
Therefore, an impeller blade receives the fluid which flows in the direction which is not preferable, and as a result, a high strength is required for the impeller blade. In realizing an impeller blade having a high strength, a plate thickness or a material of the impeller blade is restricted, and manufacturing costs increase.
Regarding a strength of the torque converter, JP 1-307565A (Reference 1), JP 11-2304A (Reference 2), and JP 2013-155857A (Reference 3) are known.
Reference 1 discloses a technology, in which a cutout portion is provided at a part of a press-fitting portion with respect to an impeller shell on an inner circumferential side of an impeller blade, and after the impeller blade is press-fitted to the impeller shell, by performing caulking so that a part of the impeller shell is put on the cutout portion of the impeller blade, a bonding force between the impeller blade and the impeller shell becomes strong.
Reference 2 discloses a technology, in which a projection is provided in a tab of an impeller blade, and as the projection abuts against a recess of an impeller shell, positioning and fixing of the impeller blade with respect to the impeller shell are reliably performed.
Reference 3 discloses a technology, in which a slit-like insertion hole is formed in an impeller shell, an insertion piece is formed in an impeller blade, and as the insertion piece is inserted into the insertion hole, generation of unevenness in a fixed state of the impeller blade and the impeller shell is minimized.
However, there is a problem that manufacturing costs are high in all of References 1 to 3. Specifically, in Reference 1, after press-fitting the impeller blade to the impeller shell, it is necessary to add a process of performing caulking so that a part of the impeller shell is put on the cutout portion of the impeller blade. In Reference 2, it is necessary to add a process of forming the projection in the tab. In Reference 3, it is necessary to add a process of forming the insertion piece in the impeller blade.